The blood flow rate is an important physiological parameter, and researchers have proposed many methods to measure the blood flow rate. With advance of medical technology, non-invasive measurement methods have gradually replaced the conventional invasive measurement methods. Among the non-invasive methods, the vascular visualizer and the Doppler ultrasonography are the most popularized technologies. However, the abovementioned two methods need bulky apparatuses and a lot of consumables. Thus, the application thereof is constrained.
With emergence of wearable devices, many consumers wear wearable devices to detect the physiological signals in real time. Owing to bulky volume, the users are unlikely to wear the current blood flow rate devices, including the vascular visualizer and the Doppler ultrasonography device.
A Taiwan patent No. 1517838 disclosed a blood flow sensing device, which comprises a sensing module, a comparing unit and a display unit, wherein two different areas of a testis or scrotum are respectively defined to be a comparison measurement area and a reference measurement area. The sensing module emits a light beam with a specified wavelength to the comparison measurement area and the reference measurement area and receives the light beams reflected from the comparison measurement area and the reference measurement area to obtain comparison pulse information, reference pulse information, comparison blood oxygen concentration and reference blood oxygen concentration. The comparing unit respectively compares the comparison pulse information and the comparison blood oxygen information with the reference pulse information and the reference blood oxygen information to output a relative blood flow state of the blood vessels of the comparison measurement area and the reference measurement area. Next, the comparing unit determines the relative blocking state or disconnection state of the blood vessels of the comparison measurement area and the reference measurement area according to the relative blood flow state. Then, the display unit presents the relative blood flow state. The abovementioned conventional technology needs multiple groups of sensors to measure the comparison measurement area and the reference measurement area at the same time. Further, there is a distance between the comparison measurement area and the reference measurement area. Both factors are unfavorable to the application to wearable devices. Besides, the conventional technology cannot learn the blood flow rate but can only obtain the blood flow state.